This invention relates generally to the protective seals of material covering container openings, and deals more particularly with an improved method and apparatus for lifting the corners of a protective patch of material used to seal a cartridge type dispenser containing viscous food sauces.
Protective seals are used in a wide number of containers. Oftentimes, the seals prevent the contents of the container from escaping before the initial use of the product within the container. The seals are generally made from thin, malleable metals such as aluminum. In addition to preventing premature escape of the container's contents, the aluminum patch prevents air and other contaminants from interacting with the contents of the container. Further, the seal may give the user added assurance that no tampering occurred with the contents of container before the initial use. Thus, seals are particularly useful for containers for storing food products and pharmaceuticals which may spoil and are affected by contact with air and various contaminants. Seals may be placed over the openings of containers in a variety of manners. In some instances, the seals may extend beyond the edge of the opening so that the periphery of the protective seals are not in proximity with the surface of the container. For instance, protective seals used to cover the circular openings of aspirin bottles use protective seals which extend somewhat beyond the lip of the opening, but may still allow the cap of the container to be screwed to the bottle. When the cap is removed, the user simply grasps the exposed tabs and pulls the protective seal from the remainder of the bottle. However, for other containers, it is either undesirable or impracticable to have the edges of the protective seal extend beyond the surface of the container.
One example of such a container is prevalent in the retail food service industry. In fast service restaurants and other retail food establishments, food sauces of various types must be dispensed in a large number of portions each containing a relative small quantity of sauce. Some sauces such as vinegar may be placed in conventional bottles which are compressed by the user to force the contents out of the bottle. However, sauces such as mayonnaise are relatively viscous and are not efficiently and accurately dispensed from bottles formed from flexible materials. It has been found to be convenient to package a wide variety of food sauces in cartridges from which the sauces are dispensed by hand held dispensing guns similar to caulking guns.
The cartridges used in these dispensing guns typically employ composite discs having disk valves at one end of the cartridge to evenly distribute the sauces when forced by the plunger of the cartridge gun. Likewise, the valves retain the sauces within the cartridge when the plunger of the gun is not actuated. Reference may be made to U.S. Pat. No. 4,830,231 for a more thorough discussion of this type of disk valve. Generally, each composite disc comprises at least one paperboard layer framing the valves formed on a disc valve layer. The disc valve layer is typically made of polyethylene and has a number of slits or similar valves cut into the layer to allow the food sauce to flow from the container. Protective laminate patches comprising thin foil seals are placed over the disc valves of the composite disc substrate to seal the contents of the container. The seals are adhered to the disc valve layer substrate along a circular path at the interior of the edges of the foil laminates. The peripheral edges of protective seals extend beyond the framed PET disc valve layer and terminate at and overlap with the paperboard layer. When the end user wants to open a new container, the user pulls one of the corner tabs of the foil seal from the cartridge disc substrate and peels the protective foil laminate away from the remainder of the container.
In prior art methods used to manufacture cartridge discs, the foil laminate patches were cut before being adhered to the disc valve. The rectangular laminates were adhered to the paperboard layer of the disc and the tab area between the adhesive connection and the edge of the disc was relatively separated from the disc and easy for the user to grasp. Thus, the seals were easy to remove. The discs were manufactured by one machine and the protective seals were applied on another machine. This required that the discs be moved from the disc formation machine to the seal applicator machine and led to a number of inefficiencies. For instance, the slit valves on the disc could become lodged between the tabs and paperboard base of the adjacent disc when the discs were stacked.
A new manufacturing process was developed in which the foil tab was applied on the cartridge disc formation machine. Essentially, portions of foil from a supply roll are adhered to the upper surface of the cartridge disc after the composite disc is formed. The foil laminate is then cut from the roll. The depth of the cut severs the foil laminate from the foil supply roll without cutting the paperboard layer underlying the edge of the protective seal on the cartridge disc. Since the manufacturing method allows the foil laminate to be secured to the cartridge disc in one machine, one step of the process is eliminated and the associate inefficiencies are removed. However, the cutting technique tends to embed the edges of the protective foil tab patch into the paperboard layer and the foil laminate is difficult to remove.
Accordingly, the need exists for a tab lifting method and apparatus which will effectively lift the embedded tabs of protective seals applied during the disc formation process. The present invention fills these and other needs and overcomes the drawbacks associated with the prior art.